Desulfurizing adsorbent and process for preparing same



Patented Dec. 30 1947 DESULFURIZING ADSORBENT AND PROC- ESS FOR PREPARING Robert: G. Capell: and- Robert G. Amero; Warrem,

Ba. assignors. to Floridin; Company, Warren, Ba.,.a.corporation-.of Delaware.

No-Drawing; Application J une l', I945; Serial-1N0. 59-75152 zlclaimsr (Cl. 252.-190.)I

This inventiomrelatessstn axnew; product; and process of producing the same, useful in the catalytic purification, desul'fnri'zation, and conversion ofhydrocarbon gases and" liquids. It is primarily concerned, with a novel catalytic. mass. containing as essential elements an aluminous carrier material and a finely divided. activated metallic compound carried thereby. More specifically, the invention contemplates the preparation of a new hard stable granular activated product containing,

a: mixture 1 of. iron. oxide. andfullerls. earth of the Georgia-Florida type, and'the novel'productresulting therefrom In the prior art the removal ofsulfur'present as hydrogen sulfide from gases has been practiced by the so-called dry box purification process, whichutilizes-finely-powdered-irorroxidedeposit-ed on wood shavings, the combination being known to the artias iron oxide sponge? A number of disadvantages atten'dant upon this prior art proc' ess are that the sponge isbulky andrequires the use of larg-e-volumesof the same; regenerationof When. this sponge material; of. the; prior art is revivified; the. following. reactiontakes place All of these difficulties aresavoided and solved thepnesent invention, whereint a. relatively small; amount; of; catalyticmassvreplaces the bulky sponge. of; large volume which. permits;many re generations. of. the masswithoup discarding! the same and; which permits, the. entire massztorbe regenerated; in. place. in. the vessel. intwhich it. is

usedhwithoutl the trouble of; emptying the: same; which permits. the-removal" of. all the sulfur formed. during revivification, so, that-sulfur;- built up. is;substant'iall"yt eliminated.

The presentinventicnntilizes,fulleriseearthl as the: carrier; or. support for. activated; iron oxide, and thusallows. theluse. of a wide variety of con.- ditions for; regeneration; and use; In accordance Withrth present; process,,the transfer of sulfur inthe. form of; hydrogen sulfide from the gas or liquid to be purified is accomplishedby reactions similar: to. the above, aszin: the oldiron sponge process; but: the: revivified. mass: of material, is cleared; of sulfur? at: a. high. temperature and by the use of steam;.whereby the sulfur: is burned ,to S02: atia: temperature above, 500 F. andwhereby iron: sulfideispxidized: or regenerated. back to iron oxide by. air andisteamr The specific. reactions during: regeneration are. as. follows... With the presence of steam only thefollowingrtakesiplacet The catalytic mass can be virtually completely regenerated according tothe aforesaid reaction, but thereaction takes place slowly as the regeneration approaches completion. However, with the introduction of air or any oxygen containing gas the? following exothermic reaction occurs in addition to the aforesaid reactiorn. allowing the regeneration to be completed in an appreciably shorter time;

and at the temperatures of 500. Rand over, this takes place:

The-liberation of heat is beneficial to the regeneration as. it vaporizesi any sulfur not eliminated as'gaseous S02 and sweeps out any oily; cracked or polymerized products from the gas being treated.

A further feature of the invention is the removal of. mercaptans (thiols) from gases, liquids, and" petroleum distillates. This. is of particular significance, since the old" dry box purification process cannot be usedifor'removal of mercaptans from. liquids, or petroleum. distillates, Thev catalyticmassoi thepresent. inventionmay be applied to; petroleum distillatesz containing; other: sulfur containing compounds, such-as.

Thiophanes Thio-aldehydes- Thiophene Thio-ketones Polysulfides" Penthiophene' Sulfonioacid's Thionaphthene' Sulfoxides- Diphenylenesulfide' Sulfones Thianthrene;

As. an example of: thepreparation. of f the catalyticmaterial: ofzt-hespresent ,-invention;..iron.oxide is thoroughly mixed with fullers earth containing a sufiicient amount of its natural water of hydration to preserve its gelling properties. A third ingredient, the purpose being to supply alkalinity to the mix, such as sodium carbonate, may be added to the mixture. Water is then added to give plasticity to the mass, and the whole is pugged, then extruded or pelleted to form shapes,

of 700 to 900 F., or higher, should be used for activation. When subjected to temperatures of this order, fullers earth v becomes resistant to water and loses its power to gel or form a mud. Further, it has a binding action on the iron oxide, forming a hard body with the oxide, which can be ground and meshed to give a granular product of good mechanical strength, chemical activity and adsorption capacity.

Such a composition of material will selectively adsorb hydrogen sulfide from gases and will adsorb hydrogen sulfide and mercaptan sulfur from liquids, or by a diiferent method of use will convert hydrogen sulfide and mercaptan sulfur in liquids to a form that for most purposes is much less objectionable. It can be regenerated in place with the use of steam and air to a high degree of capacity and efiiciency.

Examples of the invention are as follows:

EXAMPLE 1 291 grams of air dried Georgia-Florida fullers earth, finely ground, was intimately mixed dry with 872 grams of iron oxide having the following analysis:

To this was added 430 ml. of distilled water and the whole mass kneaded together and extruded. .The extruded rods resulting were then air dried on the floor, grounded to a /20 mesh particle size, activated to equilibrium weight at 1000" F.

The activated granules were then weighed into a U-tube and hydrogen sulfide gas introduced. The test was discontinued when the exit gas discolored lead acetate paper, at which time the mixture was found to have adsorbed 3.9% of its weight in hydrogen sulfide.

EXAIVIPLE 2 568 grams of finely ground, air dried Georgia- Florida fullers earth was intimately mixed dry with 1704 grams of activated iron oxide of the analysis of Example 1. The mass was then kneaded with water and extruded. After air drying, it was ground and screened to he mesh and activated at 800 F. for one hour. 195 grams of the activated mixture was charged to a straight glass 2.6 cm. diameter tube to give a 42 cm. column on top of a wire supporting screen. Hydrogen sulfide gas was then introduced. The exit was tested for hydrogen sulfide with lead acetate paper. The test was discontinued when t wl became discolored, at which time the adsorbent had taken up 33.2% of its weight in hydrogen sulfide. The adsorbent was saturated with hydrogen sulfide and regenerated in place four times by the use of steam and air. The capacity after the fourth regeneration was 24.7%. Regeneration was carried out as follows:

1. After the hydrogen sulfide stream was shut off, superheated steam was introduced into the column.

2. When the column temperature had reached a constant value, as evidenced by the temperature of the exit steam, air was introduced into the bed, along with the continued introduction of steam. This caused a rapid rise in temperature and greatly increased the effectiveness of the regeneration by elimination of sulfur as sulfur dioxide, as well as hydrogen sulfide and elemental sulfur. After cooling down, it was ready for reuse. A typical time-temperature record of the exit regenerating gas is as follows:

TABLE I Exit Tem- STEAM ONLY EXAMPLE 3 A 15 inch column (140 grams) of /60 mesh iron oxide-Floridin mixture, activated at 900 F. was placed in a glass tube and a naphtha solution of mercaptan sulfur solution containing .00254 gram per 25 ml. was percolated through at a rate of one ml. per minute. 10,500 ml. of mercaptan solution was passed through the column before any mercaptan was detectable in the exit naphtha. This corresponds to a yield of 18,000 gallons per ton and a capacity for mercaptan sulfur of 1.5%. The introduction of naphtha was continued although the efficiency of mercaptan removal decreased, but at 11,700 ml. (20,000 gallons per ton) through-put, the adsorbent was still remov-' ing 72% of the mercaptan sulfur entering.

EXAMPLE 4 A raw gasoline having an initial boiling point of 98 F. and an end point of 388 R, which was sour to the Doctor test and which contained 033% sulfur, was percolated at a rate of 3 ml. per minute through a 15 inch column of %0 mesh fullers earth-iron oxide mixture, activated at 1200 F., and having a composition of by weight of iron oxide. 'Ata yield of 19,050 ml. (32,743 gallons per ton) 58.2% of the mercaptan sulfur entering had been removed and the com posite yield was sweet to the Doctor test.

assesses EXAMBLE 5 A test unit tower was charged. with 1.1.. pound at he mesh.- ful s earth iron oxide mixtur activa cd at 1200 F. and a natural as contain n 30 g a ns 0f sulfur per L00 cubic feet at a maximum pressu e f 36 pounds per sq a inch. a passed therethrough. After two hours" run hydrogen sulfide was detected with lead acetate. The gas was allowed to, continue flowing over.- night, regeneration being carried out the next morning. Superheated steam was admitted to the test unit tower, raising the temperature to 500 F. The introduction of air and steam into the tower caused a rise abruptly from 500 to 640 F. It was then allowed to stand overnight to cool.

While rulers earth. or the Georgieida type is the preferred carrier, other types of fullas earth may be used. Iron oxide is the pre'-. ferrcd metallic oxide, but. the invention is not restricted thereto. Zinc oxide, copper oxide, and nickel oxide may be used singly or in combination, or else in conjunction with iron oxide. The dry box container may be replaced with other suitable containing means. The extrusion step referred to may besuch as is carried out in accordance with the description of the Hartshorne Patent No, 2,079,854, May 11, 1937, although the invention is not slavishly restricted to an extrusion step. The use of Raschig rings prepared The next day a test run at a flow rate of 120 cubic 7 feet per hour (25 feet per minute) produced gas that was sweet to lead acetate for approximately eight hours.

EXAMPLE 6 mercaptan sulfur was completely removed and the total sulfur content of the naphtha was substantially reduced. These results are summarized in Table II.

TABLE II Removal of sulfur from naphtha in the vapor phase ori ma} Naphtha treated Naphtha treated Sulfur present in untrgeated with iron oxide w1th lron oxlde the form ofma htha Floridin mixture Floridin mixture P at 400 F. 500 F.

Per cent Per cent Per cent Hydrogen sulfide- 0038 0000 0000 Mercaptan sulfuix 0560 0000 0000 Elemcntarysulfun 0000 Trace 0005 is fides. 0157 0031 0038 sulfides 0159 0221 0225 Residual sulfur. 0221 0181 0175 Total sulfur 1135 0433 0443 From all the above tests it will be seen that the adsorption capacity of the catalytic product is approximately up to 7% of its weight for hydrogen sulfide, and its adsorption efiiciencyis practically up to 100%, up to its full capacity. When made into an adsorbent bed, after the bed has become exhausted for adsorption of H28, the gas flow should be cut off and steam used to flush out all the remaining vapors. The bed is then heated up to 450-500 F. After the temperature of the bed reaches a steady state, a small quantity of air is introduced cautiously and simultaneously with the steam, the temperature of the bed being controlled by the introduction of the air so that it does not exceed 700 F. After the react on is completed, the temperature returns rapidly to that of the introduced steam, at which point the introduction of air is discontinued and the steam is continued until all of the air has been flushed out of the bed. The bed may then be cooled by one or a combination of the following:

A. Cooling coils.

B. Inert gas such as nitrogen or C02.

0. Introduction of cold, sweet gas.

D. Natural cooling, such as standing overnight.

Number from the new catalytic material is contemplated. In the conversion of hydrocarbons, whereby gasoline is produced by a liquid or vapor phase cracking process, the new catalytic material may be employed.

The fullers earth and iron oxide may be mixed in any proportions; the preferred proportions range from 70-90% iron oxide by weight. An agent to confer alkalinity on the catalytic mass may be an essential part of the originally used iron oxide or it may be added to the mixture before or after activation thereof. Sodium carbonate is preferred to confer alkalinity, but other alkalies or basic substances may be utilized without departing from the spirit and scope of the invention.

Although we prefer to use fullers earth of the Georgia-Florida type, such as has been generally known by the name Floridin for many years, it will be understood that we may use any fullers earth or similar material that can be made into hard granules and to which the iron oxide or other ingredient can be firmly bonded as herein disclosed to give a suitable adsorbent.

While air is the most practical oxygen-containing gas to use in regeneration, cylinders of compressed oxygen may be economically purchased and used. Flue gases could also be used, although their oxygen content would be rather low.

We claim:

1. The method of preparing a new desulfuriz ing adsorbent which consists solely of fullers earth and iron oxide, the iron oxide being in greater amount than the fullers earth and in amount of 70 to by weight, said method consisting in mixing the fullers earth containing a sufiicient amount of its natural water of hydration to preserve its gelling properties with iron oxide, plasticizing the mixture, extruding the mass, and heating the extruded mass at a temperature from 230 F. to 1400" F, to activate the same.

2. The method in accordance with claim 1 in which the mixture is rendered alkaline.

ROBERT G. CAPELL. ROBERT C. AMERO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date 1,903,528 Herthel et a1 Feb. 26, 1929 2,053,960 Keller Sept. 8, 1936 2,073,638 Houdry Mar, 16, 1937 2,078,247 Houdry Apr. 27, 1937 2,079,854 Hartshorne May 11, 1937 (Other references on following page) Number UNITED STATES PATENTS Name Date Greger Nov. 4, 1941 Greger July 13, 1943 Cross Oct. 11, 1932 La Lande, Jr Nov. 28, 1944 Morrell Nov. 2, 1937 Welty Jan, 30, 1945 Gray Nov. 28, 1933 Newsome et a1 June 12, 1945 Number 10 Number Name Date Drennan Nov, 3, 1942 Connolly July 13, 1943 Retaillian Aug. 9, 1938 Schaafsma Dec, 5, 1944 Schwarcman Oct. 1, 1918 FOREIGN PATENTS Country Date Great Britain Aug. 24, 1922 

